I am considering trading in Modern Warfare 2 (yes, I bought it. But Now I realize my mistake) for Battlefield: Bad Company 2. With the money left over from a gift card the credit from MW2 would be enough to get me the game.
Would anyone like to share their experiences with this game?

Just to make sure, that's a console version right? As if it's a PC one, you can't trade it primarily due to Steam.

I have played the SP of MW2, the SP and MP of MW, and the SP and MP of BC2.
BC2 is the best :p
SP-wise, it has fewer epic setpieces than the Modern Warfares, but holy hell is it fun. And grenades aren't insta-death, so that is worth a lot. Plus, nothing beats blowing a hole in a wall with a 40mm grenade launcher so that you can hop up to the thieves highway.
MW is all about the set-pieces. BC2 has them, but the general gameplay creates even better set-pieces through the amazing audio and visuals.
MP-wise: BC2 is also about unlocking stuff. But it is a lot less frustrating. Even when you are on team n00b and getting hosed down as you try to assault a base, it is fun. Even when people spam grenades to kill you, it is fun. Point of reference, I dislike most of the Battlefields (I like Battlefront, but that is because I like Jango-clones :p), but BC2 is just great.

I can't stand MP shooters and I'm getting this. And I'm excited. Weird.
Nice to see a MW2 convert. :)

BC2 is an amazing game IMO. Yes, it won't still get played 10 years from now, but I seriously doubt MW2 will either....
Both SP and MP, the game rocks. The attitude of the game in SP is a breath of fresh air.
The destruction of the environment in both SP and MP is something to be experienced and then hate it that other FPS games don't have it to this degree...

As long as you stay on low ping servers it's great. Don't play daily though, any online shooter will break you down if you play it too much. I am currently taking a single week break after a month of hard playing.
Online it is fun, but once you unlock everything you stop worrying about the unlocks and just focus on the great gameplay. I actually find myself using crappy guns just to say I killed people with them now and don't care about getting the best anymore. It's not as lame as BF2142 with nade spam and whatnot, reloading grenades takes longer and the maps are so big there are no more bottlenecks you can stall a team with, gameplay is much more fluid than BF2 or 2142.

I haven't tried the multiplayer yet (due to the fact it's supposed to be buggy as hell. Don't want to ruin it for myself). But the single player is a blast. Very solid mechanics and weapon balancing which bodes well for the multiplayer. It also looks bloody good maxed out.

Yes, it's for the PS3.
I suppose I'll give it a go then once I find time to make a trip to a game store.

Oh, one random question:
Apparently there was 0-Day DLC for BC2? Some map pack or whatever. How do those of us with the Steam version get this?

Fixed with the latest patch I think.
Don't think version matters. Pretty sure you redeem your code in-game and it gets added to the dedicated servers automatically. Another pack was released yesterday, and apparently lots more will come.

BC2 is awesome.
The Steam version automatically gets the new map packs because everyone on Steam bought it new.

I'm still wondering if I'm going to like this more than the other Battlefield titles I've played (mostly 1942 and BF2, with a bit of Vietnam recently).
You have to unlock a lot of stuff at the beginning, though. (Notably, playing medic with the starting PKM really, REALLY sucks when you keep getting dropped with ease; things start getting easier with the M249 and Type 88, though, and the dreaded M60 does wonders for fending off foes so you can revive any downed teammates.) BF2 at least had decent default weapons for the most part, and 1942/Vietnam hadn't introduced unlocks yet.
Positional audio cues don't seem as distinct as the older games, maybe because they didn't use EAX/DirectSound3D/OpenAL this time. They're definitely there, but too subtle to notice against all the ambience and whatnot for some reason.
Gameplay-wise, it's definitely more focused and fluid, as you'd expect of a game with a 32-player cap rather than the usual 64-player cap of the older iterations. I guess that part of it has to do with the new-to-PC-players Rush game mode, where NOT hitting the M-COMs hard and fast will be a sure loss for the attacking team. In any case, the feel is most definitely NOT traditional 1942/Vietnam/BF2.
The destructable buildings and slightly deformable terrain do change things up significantly from past titles. Liked to take cover in one of those wooden shacks on Wake Island because they'd hold up against tank shells? Not happening here-you'll just see a gaping hole where your precious cover used to be, and you might have been blown away along with the wall if you were too close! The terrain craters left behind from things like mortar strikes may not seem like much, but then you realize the somewhat bothersome effect they can have on tanks and other such vehicles when you try to drive over them. I also recall seeing one of the M-COM stations in Port Valdez basically reduced to a giant rectangular crater with the target crate somehow still intact.
One thing that really worries me, though? EA and DICE still own all those dedicated servers-they're apparently just being rented. No LAN options, either. I'm concerned because several years from now, they may just pull the plug on all those servers and make me feel like I wasted US$20. Something similar might happen with BF2 if the account server goes down, but I'm pretty sure that can be played through LAN with offline accounts, and we have tunneling/VPN apps to get around that anyway. 1942 and Vietnam should have nothing to worry about as long as someone wants to host a server for them.

It should be automatic with the Steam version.
I got the digital version from the EA Store on Sunday, and I have both DLCs without having to type in a VIP code. When you run the game, it runs a "version check", and during that it will download any available DLCs.